The BBC's Middle East analyst Roger Hardy says it appears the Islamic movement is putting practical considerations ahead of ideological ones - they are hoping women may have a better chance than men of evading Israeli security precautions.

and

Israeli officials said the bomber tricked soldiers by saying she had a metal implant in her leg which would trigger metal detectors.

"Because she was a woman, a female soldier was sent for to search her. She used this opportunity to enter the building, a metre or two past the door, and blow up," said Israeli Brigadier-General Gadi Shamni, commander of Israeli forces in the Gaza Strip.

Indeed - one of the problems with relying upon profiling as the only tool for screening for terrorists is that the terrorists adapt their tactics. When you start concentrating on middle-eastern men, they'll send a woman. Or a person who is not (or does not appear to be) middle-eastern.

Perhaps they'll dress one up as a nun, or hide the explosives in a wheelchair or other apparent medical device designed to get past security.

We should not underestimate our enemies. They are actively looking for ways to successfully attack us.